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Biomedical subjects

M Sameshima

Publications and source records attributed to M Sameshima.

At least 73 records · Page 4Linked to original sources
PubMed1985

Power spectral analysis of the surface electromyogram before and after a warning signal in a reaction movement.

The present study was performed to substantiate the premise that frequency components of the surface EMG before a reaction movement change after a warning signal (S1). Twelve subjects extended rapidly the trunk from a bent position in response to a moving signal (S2) 2 sec after S1. The movement was repeated 20 times. Bipolar surface EMG recordings were made from the erector spinal muscle. A minicomputer calculated power spectra of the surface EMGs for 2 sec before S1 and for 2 sec from S1 until S2 in each trial. From each spectrum, the mean frequency (MF) was calculated. EMG itself was examined. Statistical comparisons of differences between the mean values of the MF before and after S1 showed that a significant difference was found in 5 subjects. For the subjects, the mean value of the MF after S1 was a lower value than that of the MF before S1. Increase of EMG power in frequency range from 30 to 50 Hz was observed in the averaged EMG spectrum after S1 in the subjects. Slowing of the surface EMG during the preparatory period from S1 until S2 was often observed in the subjects. These results show that the power spectrum of the surface EMG after S1 shifted to lower frequencies and suggest that the EMG spectral shift is due to the slowing of the surface EMG in association with motor preparation to perform the movement.

Electromyography↗
PubMed1985

The orientation of nucleus, nucleus-associated body and protruding nucleolus in aggregating Dictyostelium discoideum.

Dictyostelium discoideum growing or developing on cellulose dialysis membranes were fixed with acrolein vapour for electron microscopy. In interphase amoebae, nucleoli began to protrude from the nuclei. The percentage of cells with protruding nucleoli increased during aggregation by a value approximately twice as high in aggregation streams as in centers. Cells in pseudoplasmodia showed only a low percentage and protrusions disappeared at early culmination stage. The protrusions did not reappear when cells from dissociated pseudoplasmodia migrated toward cAMP. Thus the formation of the protrusions did not depend solely on chemotaxis; rather, it was specific to the aggregation stage. In aggregation streams, the nucleus was anterior in the cell, with the protrusion at its anterior periphery. In contrast, the nucleus associated body (NAB) was evident at the cell's mid-point. This orientation of nucleus and NAB in the aggregating slime mould amoeba is contrary to that seen in human neutrophils or cultured mouse 3T3 cells.

Cell Nucleolus↗
PubMed1985

[A study of tracking behavior in adults with cerebral palsy: on muscular contraction mechanism and motor perception].

Two tracking experiments were carried out to investigate the motor control system in adults with cerebral palsy. The first experiment analysed the frequency response characteristics and the surface electromyogram from biceps brachii and triceps brachii, when the cerebral palsy subjects made isometric contractions during the pursuit tracking task with sine wave targets. Patterns of reciprocal innervation of the antagonists explained the frequency response characteristics of tracking behavior of the cerebral palsy subjects. The second experiment analysed perceived response velocity during the compensatory tracking task by means of magnitude estimation method. Fitting power function to the relation between the input frequency and the perceived response velocity, coefficients of determination for the cerebral palsy subjects were found to be lower than those for the normal subjects. It suggests that the cerebral palsy subjects can discriminate their response velocity less exactly than the normal subjects in manual tracking system.

Adult↗
PubMed1985

Effects of neuraminidase on lectin binding sites in photoreceptor cells of monkey retina.

Binding of sugar-specific lectins to the monkey retina was investigated with particular reference to the effects of pretreatment with neuraminidase on the photoreceptor cells. Neuraminidase-treated or untreated retinal sections were examined with a fluorescence microscope after incubation with the following fluorescein-labeled lectins: peanut agglutinin (PNA), wheat germ agglutinin (WGA), Ricinus communis agglutinin-1 (RCA-1) and Dolichos biflorus agglutinin (DBA). In the neuraminidase-untreated tissue, PNA, which is specific for D-galactose beta 1----3 N-acetyl-D-galactosamine (Gal beta 1----3GalNAc), was bound preferentially to the cones, and after treatment of sections with neuraminidase, PNA could bind to both cones and rods. WGA, which is specific for sialic acid and N-acetyl-D-glucosamine, was strongly bound to the rods but moderately to the cones without neuraminidase pretreatment, whereas neuraminidase-treated sections showed a weak binding. RCA-1, which is specific for D-galactose, showed patchy fluorescence on the basal and distal portions of the outer segments of the cones and rods, whereas neuraminidase-treated sections had uniform fluorescence throughout the tissues. DBA, which is specific for N-acetyl-D-galactosamine, did not bind to either cones or rods before and after neuraminidase treatment. These results suggest that there is a difference in the carbohydrate chains of glycoconjugates in the cones and rods: in the cones Gal beta 1----3GalNAc may be the terminal sugar as recognized by PNA, whereas in the rods this sugar is contained in the carbohydrate chain but masked by terminal sialyl residues so that those glycoconjugates are inaccessible to PNA without neuraminidase treatment.

Animals↗
PubMed1984

Capsaicin-induced neuroparalytic keratitis-like corneal changes in the mouse.

A single subcutaneous injection of 12.5-100 mg kg-1 capsaicin to newborn mice produced gross corneal changes. The changes were manifest about three weeks after capsaicin treatment and progressed dose-dependently from slight punctate vesiculations in the epithelium to diffuse edematous opacities and vascularizations in the stroma, followed by recovery in several weeks with or without residual scars. Control newborn mice with vehicle solution did not show any corneal abnormality. The most prominent histopathological feature of the affected corneas was a marked loss of nerve axons in the epithelium with associated disorganization of the epithelium. Similar corneal changes were observed with systemic capsaicin treatment to young or adult mice. The pathogenesis of the capsaicin-induced corneal changes was discussed with reference to the trophic action of the trigeminal nerve.

Animals↗
PubMed1984

Application of lectins for detection of goblet cell carbohydrates of the human conjunctiva.

Paraffin-embedded and frozen biopsies from the human conjunctival epithelium were examined by fluorescence microscopy after labeling with eight fluorescein-conjugated lectins: wheat germ agglutinin; soybean agglutinin; peanut agglutinin; Ricinus communis agglutinin-1; Limulus polyphemus agglutinin; Ulex europaeus agglutinin-1; Dolichos biflorus agglutinin; concanavalin A. The lectins were used as specific molecular probes to detect carbohydrate composition of glycoproteins secreted from the conjunctival goblet cells. The labeling pattern of goblet cells and conjunctival epithelial surfaces with various lectins suggested that N-acetyl-glucosamine, galactose, N-acetyl-galactosamine and sialic acid are contained in goblet cells and contribute to the formation of tear mucus glycoprotein. Fucose and mannose, which are present in the tear mucus, were not detectable in goblet cells.

Aged↗
PubMed1984

Preparation of Dictyostelium discoideum for electron microscopy.

Dictyostelium discoideum grew and differentiated normally on cellulose dialysis membranes placed on agar plates. This permitted the examination of cells at various stages of development, including cells during aggregation. Cells were preserved well and fixed for electron microscopy by brief exposure to acrolein vapore followed by immersion in glutaraldehyde solution.

Dictyostelium↗
PubMed1984

[Dynamic characteristics of compensatory tracking behavior in adults with cerebral palsy].

Dynamic characteristics of motor control system of adults with cerebral palsy was examined by a compensatory tracking task with step wave, sine wave and random wave targets. The velocity of responses to step wave targets by the cerebral palsy subjects was lower than that by the normal subjects. In terms of the closed-loop transfer functions in responses to sine wave targets compared with those to random wave targets, it was revealed that the normal subjects could switch their feedback tracking behavior to precognitive control behavior in order to reduce their tracking phase lag which was greater with random wave targets than with sine wave targets, while the cerebral palsy subjects could not do so. These results suggest that the cerebral palsy subjects have difficulty in generating precognitive control behavior to match sine wave targets.

Adolescent↗
PubMed1984

Binding sites of peanut agglutinin in mammalian retina.

Histochemical studies were carried out of the binding sites of a lectin, peanut agglutinin (PNA), in the mammalian retina, using lectin labeled with either fluorescein or horseradish peroxidase. In all mammalian species examined, monkey, pig, cat and rabbit, the cones were intensely labeled with the lectin but the rods were unlabeled. The cone synaptic pedicles, the inner synaptic layer, the internal limiting membrane and the retinal vessels were also labeled. It is suggested from the specificity of the PNA binding that galactosyl and/or galactosaminyl residues are present in the mammalian cones, but not in the rods.

Animals↗
PubMed1983

Localization of fluorescence-labeled lectin binding sites on photoreceptor cells of the monkey retina.

The binding of eight fluorescence-labeled lectins to the photoreceptors of the monkey retina was investigated using a post-embedding staining method. Concanavalin A (specific for mannosyl and glucosyl residues) bound to the outer and inner segments of both rods and cones, while the degree of staining was more intense in the rods. The rod outer segments showed patchy fluorescence and the proximal portions of the inner segments were diffusely stained. Wheat germ agglutinin (specific for sialyl and N-acetylglucosaminyl residues) bound preferentially to the surface of the outer and inner segments of both rods and cones. Ricinum communis agglutinin-1 (specific for galactosyl residues) stained the rod outer segments in patches, particularly strongly in the region dividing the outer and inner segments. The cones were also stained, although faintly, in the same pattern as the rods. The distal halves of the rods and cones showed diffuse weak staining and their proximal halves stained spotty. Peanut agglutinin (specific for Gal beta 1 leads to 3GalNAc sequence) bound preferentially to the cones and only scarcely to the rods. The external surface of both outer and inner segments of cones were uniformly stained; the interior of the cone outer segments was also stained, while the interior of the inner segments was not. Two lectins specific for fucosyl residues, namely, Ulexeuropaeus agglutinin-1 and Lotustetragonolobus agglutinin, bound diffusely to the distal halves of the inner segments of both rods and cones. Lectins reacting with N-acetyl-galactosamine residue, i.e. Dolichos biflorus agglutinin and soybean agglutinin, bound weakly to the distal portions of rods and cones.

Animals↗
PubMed1981

Lysosomal enzyme activities and RNA turnover rates in growing and nongrowing WI-38 and HeLa cells.

Activities of three lysosomal enzymes--acid RNase. N-acetyl-beta-D-glucosaminidase and acid phosphatase--were determined during the growth cycles of WI-38 and HeLa cells, as well as in radiation-arrested WI-38 cells. In confluent and growth-arrested cultures of WI-38 cells, the lysosomal RNase increased six- to sevenfold; glucosaminidase, four- to fivefold; and phosphatase, two- to threefold. In HeLa cells, the lysosomal enzymes also increased in confluent cultures, but less than twofold; and the RNase level increased only transiently. In both WI-38 and HeLa cells, the rate of RNA breakdown also increased as cultures approached confluency. The rate of turnover of RNA, like the level of acid RNase, was higher in WI-38 cells than in HeLa cells (4 d half-life compared to 8 d). The increase in acid RNase could be prevented by incubation of cells in NH4Cl, but the rate of turnover in the presence of NH4Cl increased just as much when cells became confluent or stopped growth. The content of acid RNase could be changed more than 10-fold without altering the rate of RNA turnover. It is suggested that the increase in enzyme level is more important for possible autophagy or increased digestion of engulfed RNA, rather than for normal RNA turnover, when growth stops.

Acetylglucosaminidase↗
PubMed1981

Dual pathways for ribonucleic acid turnover in WI-38 but not in I-cell human diploid fibroblasts.

The turnover rates of 3H-labeled 18S ribosomal ribonucleic acid (RNA), 28S ribosomal RNA, transfer RNA, and total cytoplasmic RNA were very similar in growing WI-38 diploid fibroblasts. The rate of turnover was at least twofold greater when cell growth stopped due to cell confluence, 3H irradiation, or treatment with 20 mM NaN3 or 2 mM NaF. In contrast, the rate of total 3H-protein turnover was the same in growing and nongrowing cells. Both RNA and protein turnovers were accelerated at least twofold in WI-38 cells deprived of serum, and this increase in turnover was inhibited by NH4Cl. These results are consistent with two pathways for RNA turnover, one of them being nonlysosomal and the other being lysosome mediated (NH4Cl sensitive), as has been suggested for protein turnover. Also consistent with the notion of two pathways for RNA turnover were findings with I-cells, which are deficient for many lysosomal enzymes, and in which all RNA turnover was nonlysosomal (NH4Cl resistant).

Adenosine Triphosphate↗